Research On Small-Break Accident Of Supercritical Water-Cooled Reactor CSR1000

In the "Nuclear Safety Law of the People's Republic of China",it is pointed out that nuclear facilities must meet nuclear safety standards in the design process,adopt reasonable equipment parameters and technical requirements,and provide diversified protection and multiple barriers for meeting the nuclear safety requirements.As a self-designed supercritical water reactor in China,CSR1000 has the advantages of high unit thermal efficiency,system simplification and safety.However,its safety is under great threat due to the use of high temperature and pressure of supercritical water as a coolant.That research on loss of coolant accident of CSR1000(SBOLCA)improve the design of the safety system of supercritical water reactor and ensure the safety and reliability of the supercritical water cooled reactor.Supercritical fluid and CSR1000 are selected as the research object,and it is to be established thermal-hydraulic calculation model for calculating parameter changes in SBLOCA.Using the mathematical method of multiple factor analysis the various factors of the supercritical jet discharge weight analysis,and a simple comparison between the calculation results of CSR1000 small-breakwater loss accident and the AP1000 and Super LWR reactors verified the reliability of the program.By compiling Small-break program,we can see that in all kinds of supercritical fluid pressure relief factors,the fracture pressure decreases first with the increase of time and finally tends to steady state.The lower the initial pressure of supercritical fluid is,the shorter the pressure reaches the equilibrium at the breach point.The higher the initial temperature is,the slower the pressure release rate is.However,the pressure relief velocity is faster at the later stage of breach,and the equilibrium time The shorter.The higher the initial temperature,the faster the breaking mass flow rate decreases,and the shorter the breaking mass flow rate reaches equilibrium time.The influence of initial pressure,initial temperature,breaking area and volume on the pressure relief was calculated by using the multivariate analysis of variance(ANOVA)mathematical algorithm.The calculation results show that the area,volume,initial pressure and initial temperature In the break vent pressure accounted for the weight of 8.55,7.92,4.19,1.19.Among the four influencing factors of pressure at the breach,the breach area is the most influential,followed by the initial temperature.Through the coupling of CSR1000-SBLOCA program,the accident of 2%cold-pipe small-breakage in CSR1000 was calculated.The results show that both core pressure and main steam pressure rapiddly decline after rapiddly rise,and the pressure remain in the supercritical pressure range.In the first and second process,the mass flow fluctuated up and down momentarily,until the safety system started to stabilize after receiving the corresponding signal.The first and second process of the shell temperature trend is the same,are the first rapid increase gradually decreased,and finally stabilized at a temperature near.The trend of increase in the temperature of the cladding in the second process is generally higher than the temperature increase of the cladding in the first process.However,the maximum temperature of the cladding in both processes is lower than the safety standard of 850 ? and the core stay a safe state.By comparing the CSR1000 with the AP1000 and the Super LWR,the CSR1000 and the Super LWR do not form a two-channel process at the break,but only one process channel path,ie,"single-ended break." This is different from the"double-ended break" that occurs when the AP1000 has a small break accident.The process of the small break water loss accident of the CSR1000 is close to the calculation result of the Super LWR process,which verifies the reliability of the program,and proposes that the safety valve designed for automatic infrared detection and can be automatically isolated and opened responds to the countermeasures as well as the original containment material basis.Based on the original containment material,three-tier containment shells were targeted.esigned three layers of containment targeted measures.